Al-Ghazali was an Islamic philosopher and mystic born in Persia (modern day Iran) in 1058 CE. He is considered to be one of the most important Muslim philosophers, and his critique of Greek philosophy would change the direction of Islamic philosophy. Al-Ghazali is known for rejecting Neoplatonic and Aristotelian ideas, such as the world being eternal rather than created, that God’s nature means he does not know particular things, and that resurrection is impossible. In contrast, he used logic and reason to put forth his own Islamic philosophy which is in line with traditional Islamic beliefs. Additionally, Al-Ghazali is known for having undergone a spiritual crisis, after which he would become a mystic. In his life and writings, he popularized Sufism (Islamic mysticism) and showed how it could be combined with Orthodox Islamic theology and religious practice.

Al-Ghazali was born in Tus, Iran where he grew up studying religion and philosophy (falasifa). A professor at the University of Baghdad, he left after having a spiritual crisis. He would travel around living a solitary, modest lifestyle and make the pilgrimage to Mecca. He became a Sufi, and would come to teach others that mysticism is the path to true knowledge of God. He saw philosophy as limited, while mysticism allows one the possibility of experiencing the unlimited and “seeing” God.

Al-Ghazali is famous for both summarizing the writings of earlier Islamic philosophers such as al-Farabi and Ibn Sina (aka Avicenna) in his work The Intentions of the Philosophers, as well as for sharply critiquing them and the Islamic tradition of embracing Greek philosophical ideas in his work The Incoherence of the Philosophers. While he used logic to formulate his critiques, he would reject three Greek philosophical ideas which were counter to traditional Islamic belief.

First, he rejected the philosophical belief that the world is eternal. This belief was based on the idea that God could not have changed his mind, and therefore for the world to have been created at a specific moment in time wouldn’t make sense. The world would therefore have to have always existed. Rather than simply disagreeing with this as a theologian, al-Ghazali wanted to prove philosophically i.e. through logic and reason, that the belief that the world is eternal does not make sense (i.e. is “incoherent”). He does this by explaining that the creation of the world does not mean that God changed His mind, because the creation of the world would have always been a part of God’s plan. Creation is merely the unfolding of this unchanging plan.

Second, al-Ghazali rejected the philosophical belief that because of God’s nature as an eternal being, he would only know the “universal” nature of things, rather than their particular features. For example, a man would be known as a man, but not as a particular man. This philosophical belief was based on the idea that since the things of this world are constantly changing, and God does not change, he would therefore only know the things that don’t change (such as man’s nature), and not the particular things that do (such as getting a new job). Similar to his rejection of the philosopher’s argument for why the world could not have been created, al-Ghazali explains that if God knows all, he would have knowledge of all the changes that happen to us even before they’ve occurred. Everything is simply the unfolding of God’s plan.

And third, he will reject the philosopher’s claim that bodily resurrection is impossible. This philosophical position was based on the belief that since the world is governed by cause and effect, to bring back a body that has already decayed would be contrary to the laws of science. Al-Ghazali explains that since God can do whatever he wants, he can ressurect the dead. Al-Ghazali sees causation as God creating the cause and the effect simultaneously. If he desires to resurrect the dead, just as his plan included the creation of the world, then the nature of causality as we know it could also change in that instance.

Al-Ghazali embraces the traditional belief that God is both omniscient (“all-knowing”) and omnipotent (“all-powerful”). He explains that as human beings, we have free will. At the same time, since God is all-powerful as well as all-knowing, whatever we choose to do is what he would have wanted us to choose, and he already knows whatever we will choose. In this way, free will and God’s omniscience and omnipotence are not at odds, but are two different perspectives on the same reality. Likewise, al-Ghazali believed that we are living in the “best possible world.” He explains the existence of evil in the world in that God is not obligated to do what we would like him to do. God is not responsible to anyone. He does what He believes to be correct at all times.

After experiencing his spiritual crisis, al-Ghazali realized that there is a limit to what one can known on the basis of philosophy and reason. Philosophy is limited and deals with what is finite. In order to truly understand the nature of reality and God, one must have an experience that lies beyond reason. This is known as a mystical experience, and al-Ghazali would embrace the Islamic mysticism known as Sufism. He would show that it is through the mystical experience, when one stops trying to think about things analytically but instead uses intuition, that one is able to attain a vision of the divine.

Al-Ghazali believed that as humans we are made of a body and a soul. In contrast to the body, which is a material substance, the soul is a spiritual substance and lives on after the death of our bodies. In this lifetime, we can either focus on material things and sensory pleasures, or we can turn our attention to the divine. If we are only concerned with bodily pleasures, al-Ghazali explains that when we are dead the soul will suffer because it is no longer able to fulfill these desires since it lacks a body. However, if while alive we focus on that which is divine, when the body dies the soul will be able to have an experience of the divine. In this way, al-Ghazali sees the mystic’s experience as a preview to this experience of God which is possible after death.

Also, al-Ghazali’s understanding of things allows him to support traditional Islamic religious practices. He sees these practices as allowing the body and soul to be in a state of harmony, which translates into virtuous actions such as courage and justice. He embraced both Aristotle’s doctrine of the mean, which states that balance is achieved through avoiding extremes, as well as the laws of the Islamic religion (shari‘a). In this way, al-Ghazali would embrace certain Greek ideas, and make use of reason and philosophical thought, while at the same time rejecting that which went against traditional Islamic belief.

Al-Ghazali is known as one of the most important Islamic philosophers, and is seen as the most important Muslim to have lived after Muhammed himself. He would influence not only Islamic philosophers and theologians, but also medieval Christian and Jewish thinkers such as Aquinas and Maimonides. His work would be famously criticized by Ibn Rushd (Averroes) in his work The Incoherence of the Incoherence who writes that “to say that philosophers are incoherent is itself to make an incoherent statement.” Nevertheless, al-Ghazali’s impact on Islamic philosophy was decisive, as traditional Islamic beliefs such as the Creation of the World, God’s omnipotence, and bodily resurrection were maintained. Likewise, al-Ghazali successfully brought Sufism and mystical experience from the fringes of Islamic society to the center of traditional belief and practice.